The present invention relates to compositions and processes for use in heat transfer, refrigeration and air-conditioning systems to improve the oil return, lubrication, energy efficiency, or reduce compressor wear, by using perfluoropolyether as an additive in the refrigerant or heat transfer fluid composition.
Lubricants have been used with the fluids in the heat transfer, refrigeration and air-conditioning systems to provide lubrication to the compressor and other moving parts and reduce compressor wear. However, not all the refrigerants or heat transfer fluids are compatible with all the lubricants. In particular, many HFC refrigerants or heat transfer fluids have poor miscibility or poor dispersibility with commonly used lubricants, such as mineral oil and alkylbenzene. Because the heat transfer fluids can not readily transport mineral oil lubricants through the heat exchangers, the lubricant oils accumulate on the surface of the heat exchange coils, resulting in poor oil return, poor heat exchange, low energy efficiency and the accelerated wear and tear of the compressors. As a result, the refrigeration and air conditioning industries have had to resort to the use of more expensive and more difficult to use synthetic lubricants such as polyolesters and polyalkylene glycols.
Thus, there is a need for refrigerant additives to improve oil return, lubrication, energy efficiency, or reduce compressor wear while allowing the use of conventional mineral oil with refrigerants.